1. Field of the Invention
The present invention relates to an irrigation system, and more particularly, to a system for supplying water to plants, and particularly grape plants, below the surface of the ground.
2. Description of the Background
In areas of the country which rely on irrigation during the peak of the growing season and in areas which experience periodic droughts, it is important to conserve water. The wine producing regions of California, which have an ideal climate for growing grapes for wine and have also achieved growing recognition as a source of premium wines, face these conditions. These regions have experienced a demand for land to accommodate both agricultural interests and residential needs for an increase in population. As a result of the demand for increased use of all lands in these areas, even hillside land, which has historically been difficult to irrigate, has been cultivated for vineyards. Thus, there has been an increased demand for water for agricultural and other uses at the same time that the supply of water has decreased and become less certain.
Drip irrigation methods are already widely used by grape growers and others raising high value crops. A typical drip irrigation system delivers water from a central water source to a particular field by underground plumbing systems or the like. The water is then provided to conduit or tubing which is run through the field along the rows of plants. This conduit releases the water at the sites of the plants through valves or emitters regularly spaced along the conduit. The purpose of such a system is to deliver the water as closely as possible to the plants themselves and avoid wasting it on surrounding soil. The conduit may be run on the ground near the plants, but in that case, it is more difficult to cultivate or remove weeds from the area around the plant without damaging the conduit. Weed reduction is important because the weeds compete with the vines for sun, water and nutrients. In many vineyards, the conduit is run along the rows of vines and is supported approximately 14 inches above the ground. This raised conduit allows easier cultivation around each vine, but these is less efficient use of the water since there is greater evaporation from the elevated emitters and the wind may change the direction of the water to miss the plant. The dripping water, over time, also creates channels in the soil, which leads to erosion. In some cases, thinner spaghetti tubing has been run from the emitter to the ground near the plant in a attempt to avoid evaporation. Discharging water at the base of the plant, however, does not ensure that the roots of the plants will receive the water in the direction of desired growth.
Another option has been to deliver the water directly to the roots by running an underground conduit along the rows of plants at root level or below. This kind of system, however, is very expensive to install and very difficult to repair, since leaking or faulty portions of the system would be difficult to identify or replace and any deep digging in the soil could damage the conduit.
A number of prior art systems have attempted to solve these problems U.S Pat. No. 3,876,146 illustrates a system with individual watering capabilities which is above ground and waters the plants on the surface. U.S. Pat. No. 656,887 illustrates a subsurface device for an individual plant which utilizes a cumbersome discharge nozzle. U.S. Pat. No. 4,060,991; 4,117,685; 4,350,296, and 4,928,427 illustrate other subsurface methods of irrigation in which water is delivered to the plant roots by components which run generally horizontally underground. However, there is still a need for a system which utilizes less water to produce acceptable growth, which can be simply assembled from conventional components, and which avoids evaporation, erosion and cultivation problems above the ground and difficult installation and maintenance problems below the surface of the ground.
The present invention provides an irrigation system which uses conventional conduit o feeder tubing for above ground distribution of the water through the fields and delivery to the plants without the maintenance difficulties of a below ground water distribution system, but which delivers water below the surface of the ground through deep vertical irrigation tubes to the root system of the individual plants. The system of the present invention loses no water to evaporation, reduces the water available to weeds, and avoids erosion of the soil. The invention also may utilize conventional distribution layouts, tubing and emitters. Most surprisingly, however, this invention not only solves the problems of the prior art, but it also causes the root systems of the plants to grow vertically downwardly, rather than laterally, to seek moisture and softer ground. This has led to an earlier period for establishment of the vines and to a stronger, better developed root system than with conventional methods,advantages achieved with much less water and plant maintenance than heretofore necessary.